A chemical amplification type resist composition is a pattern formation material in which an acid is generated in the exposed area upon irradiation of an actinic ray or radiation, for example, a far ultraviolet ray, and solubility in a developing solution between the exposed area and unexposed area is differentiated by a reaction using the acid as a catalyst, whereby the pattern is formed on a substrate.
In case of using a KrF excimer laser as a light source for the exposure, since a system mainly composed of a resin having as a basic skeleton, poly(hydroxystyrene) which has a small absorption in a region of 248 nm is used, a good pattern is formed with high sensitivity and high resolution. Thus, the system is superior to a conventional naphthoquinonediazide/novolac resin system.
On the other hand, when a light source having a shorter wavelength, for example, an ArF excimer laser (193 nm) is used for the exposure, since the aromatic group-containing compound essentially has a large absorption in a region of 193 nm, the above-described chemical amplification resist composition is still insufficient.
Therefore, a resist composition for the ArF excimer laser containing a resin including an alicyclic hydrocarbon structure has been developed.
With respect to an acid-decomposable resin which is the main constituting component of the chemical amplification type resist composition, various improvements have also been made. For instance, a positive resist composition containing a resin including two kinds of repeating units having an acid-decomposable group is described in JP-A-11-119434 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”) (corresponding to U.S. Pat. No. 6,207,342).
However, it has been further desired to satisfy all of line edge roughness (LWR), exposure latitude (EL), PEB temperature dependency and pattern collapsing in a higher order.